Railway signaling system



A. LANGDON RAILWAY SIGNALING SYSTEM Jan. 1, 1946.

Filed Nov. 16, 1944 a I 06% inventor M v 761071 (Ittorneg Patented Jan. 1, 1946 UNITED STATES PATENT" OFFICE RAILWAY SIGNALING SYSTEM Andrew Langdon, Brighton, N. 'Y., a'ssignor to General Railway Signal Company, Rochester,

a Application November 16, 1944, serial No. 568,674

11 Claims.

This invention relates to railway signaling systems, and more particularly pertainsv to the provision of track circuits in connection with crossovers between adjacent parallel tracks.

In most track circuit arrangements now in use in connection with crossovers, it is possible for a single car or locomotive to occupy a dangerous position on the crossover without setting the signals on the adjacent parallel tracks at stop. The reason for this is that, since adjacent parallel tracks are'usually so close together, the provision of insulated joints at the mid-point of the crossover does not represent the actual fouling or clearance point of the cross over. Thus, if a train proceeds over the crossover and just passes the insulated joints at the mid-point of the crossover, the main track which the train has just left may still be fouled by the rear end of such train because of the closeness of the crossover track to the main track.

In view of the above considerations, it is proposed in accordance with the present invention to provide an improved track circuit organization in connection with a crossover whereby a car or locomotive on any part of the crossover will place the signals of both parallel tracks at stop and maintain such condition until the train wholly leaves the track sections including the crossover irrespective of the position of the switches.

It is further proposed that the turnout fouling rail for each track of the crossover shall be associated with the detector track circuit for its associated main track in such a way as to provide broken rail protection without requiring any additional apparatus.

A still further object of the invention is to provide the proposed track circuit organization for the crossover in such a way that the continuity of the right-of-way track circuits shall be controlled in accordance with the condition of crossover detector track circuits to thereby avoid inserting the detector track circuit control into the regular signaling line circuits. It will of course be obvious that such an arrangement is particularly adaptable for use with relatively long coded track circuits for the right-of-lway where there are no line wires.

Other objects, purposes and characteristic features of the present invention will be in part obvious from the accompanying drawing, and in part pointed out as the description of the invention-progresses.

In describing the invention in detail, reference will be made to the single accompanying drawing which illustrates one embodiment oi the present invention employing conventional direct current track circuits of the normally closed circuit type. Inthe drawing, twoparallel adjacent tracks A and B are shown,- and it is assumed for convenience in the disclosure that track A is for west bound traflic and that track. B is for east bound trafic. y

The track A is shown as having a right-ofway or regular signaling track circuit with the usual track battery! and track relay TA separated'from the rest'or the stretch of track by the usual insulated joints. This right-of-way track circuit is divided into two parts including track section 6 and track section I, by reason of insulated joints forming a detector track section DA associated with the switch SA at the left-hand end of the crossover. This detector track sectionDA has a track battery 9 and a track relay TDA included in the track circuit, as will be presently described. Similarly, the track B has a right-of-way track circuit with a track battery I9 and a track relay 2:; TB which track circuit is divided into sections it and I! by reason of the insulating joints forming the detector track section DB associated with the track switch SB at the righthand end .of the crossover. The detector track section DB has a usual track battery I3 .and a track relay TDB associated therewith, as will be presently described. a a

Each of the track switches SA and SB are assumed to be of theusual manually operated type having associated therewith the switch stands 14 and I5 respectively. These switch stands l4 and 15 for the purpose of the present embodiment of .theinvention are-considered to be, of the conventional hand operated type of switch stand, but it is to be understood that the principles of the present invention may be readily applied to a crossover having poweroperated track switches at its opposite ends.

Each of theswitches SA and SB is provided with suitable switchbox or circuit controller contacts SCA and SCB respectively. These switch circuit controller contacts may be operated by any suitable mechanism, such as shown for example in the prior Patent No. 1,899,894 granted to O. S. FieldonFebruary 28, 1933, but it is to be understood that any suitable contact mechanism may be. employed providing that the contacts associated therewith are closed in their normal positions shown only when the corresponding switch is in anormal locked position,

During the passage of the west bound train over track A as above pointed out, it is seen that the opening of front contact 40 of the detector track relay TDA does not deenergize the stick relay S, because of its stick circuit including front contact 44 and switchbox contacts 42 and 43. For this reason, the stick relay S is maintained energized and the front contacts 65 and 68 are maintained closed so that the rightof-way track circuit including track relay TB' for track B is not affected by the passage of a west bound train on track A.

It will be understood by analogy that a similar operation takes place upon the passage of an east bound train over the track B without in any way affecting the track circuits of the track A. This is for a similar reason, since the opening of front contact 4| while a train is passing over detector track section TB does not deenergize the stick relay S because its stick circuit is still closed.

Should an east bound train be on the detector track section DB at the same time that a west bound train is proceeding over the detector track section DA, both detector track relays TDB and TDA would be deenergized opening their front contacts Al and 40 respectively. However, under such a traflic condition the stick relay S is not released by reason of the continued energization of its stick circuit. This is a necessary requirement since the east bound train might remain on the detector track section DB for some time after the west bound train has proceeded well beyond the point in the stretch of track where it would cause the signal LA to remain at stop or caution: and if it were not for the stick circuit of the relay S, the presence of the train on the section DB would maintain the relay S deenersized which in turn would undesirably hold the signal LA at stop. Thus, it is seen that the control'of traffic on the tracks A and B is entirely trainman then operates the track switch SB to its reverse position so that the train can proceed over the crossover. As soon as contacts 35 and 31 are opened, the detector track relays TDA and TDB are both deenergized. The openin of their front contacts 40 and 4| allows the stick relay S to drop away since its stick circuit is also opened at switch box contact 42. As the train passes over the crossover its Wheels would continue to shuntthe track so that the track relay TDB would remain dropped away until the train has assed beyond the insulated joints 23 even if the track switch SB were restored to normal. It will of course be understood that, when the train i to the left of insulated joints 23, the detector track relay TDA is shunted and drops away. It may be that the trainmanwill restore the track switch SB to its normal position before operating the track switch SA to its reverse position, as might happen with a very short train or with a locomotive on a long crossover; but, even though the switch box contacts of switch box SCB are restored to their ,normal positions, the detector track relay TDA remains deenergized due to the train shunting the detector track section DA. Also, detector track relay TDB may be picked up since the switch box contact 31 is restored to its normal position, but the stickrelay S remains deenergized since the contact of the detector track relay TDA isopened. Under this condition,the track relay TB for the right-of-way track circuit of the track B will remain deener-i gized since the open condition of front contact and 68 of the stick relay S removes the connection of the track section II with the track and track relay TA from the time of the initial opening of the track switch SB until the train has moved westwardly beyond the track section 6. When the train has traveled to the left out of the detector track section DA so that both of the detector track relays TDA and TDB are picked up with both track switches SB and SA in normal positions,-the pick up circuit for the stick relay S is closed and the track relay TB for track B is rendered dependent upon the traffic conditions of track B alone, but the track relay TA is not re-energized until the train moves to the left out of track section 6. 1 N

In view of the above, it will be evident that the signal of two adjacent parallel tracks are independent of each other until the switches of the crossover are initially operated to reverse positions, and thereafter the signals for both tracks are held at stop independently of the position of the track switches until both detector track circuits associated with the switches become unoccupied. In this way, it is impossible for a train or a locomotive to remain standing on the crossf over with both switches normal without holding the signals on both tracks at stop. This avoids any possibility of a train moving over the crossover from fouling or interfering with the passage of a train on the main track it has just left. becausetrafiic is held up on such track until the right of way is established as being safe.

As above mentioned, with the detector track circuits thus organized, the turnout fouling rail at each end of the crossover and associated with its respective switch, is included in the associated detector track section in series therewith in such a way as to provide broken rail protection, that is, if this turnout fouling rai1 should become broken, the associated detector track section would b interrupted and thus betray the condition by reason of the continued deenergization of the associate detector track relay.

In the particular arrangement chosen for the embodiment of the present invention, the condi-- tion of the detector track circuits adjacent the opposite ends of the crossover as well as the con-' dition of the stick relay acts through the medium of the track circuits of the right-of-way to hold the respective signals LA and RB at stop without the use of additional line wires for this pur-' pose. Also, it is assumed that each of th signals is provided with line circuit control which is governed in accordance with traffic conditions in advance so as to give the proper signal indications in accordance with the presence of trains in track sections in'advance. It will be appreciated that this manner of imposing th detector track circuit conditions and the associated stick relay cluding the rails of its section and the segregated rail section of said crossover next adjacent its switch in series with a track rela and a source of track circuit energy, whereby a train passing over said crossover shunts the track relay of each section until the train passes said intermediate point in the crossover, a stick relay having a pick up circuit including front contacts of the track relay for each of said two sections and having a stick circuit including contacts opened whenever either or both of said track switches are operated to their reverse positions, and signal control means for each parallel track rendered effective to allow the passage of trafiic only providing said stick relay is energized.

8. In combination, two parallel railway tracks each provided with an insulated detector track section, a crossover having a track switch at each end for connecting said two detector track sections, each of said switches including the usual frog for one of the rails of the crossover, an insulated joint in each rail of said crossover at an intermediate point, circuit means connecting the section of crossover rail adjacent a switch frog to the main rail of the associated track section including that frog, an insulated joint in the turnout stock rail near the switch at each end of said crossover so as to provide a segregated rail section in opposite rails of the crossover on opposite sides of said intermediate point, a track circuit for each detector track section including the rails of its section and the insulated rail section of said crossovernext adjacent its switch in series with a detector track relay and a source of track circuit energy, whereby a train passing over said crossover shunts the detector track relay of each detector track section until the train passes said intermediate point in the crossover, track sections at the opposite ends of each of said detector track sections included in a track circuit for its track, such track circuit having a track relay and a track battery at the extreme ends of the two sections forming the track circuit, a stick relay having a pick up circuit including front contacts of said detector track relays of said detector track sections and having a stick circuit including contacts open whenever either one or both of said switches is operated to reverse positions, and circuit means for connecting the near ends of the track sections on each side of a detector track section for each track and including front contacts of said stick relay.

9. In a track circuit organization for a crossover connecting two parallel tracks a detector track section associated with each of the track switches at the opposite ends of the crossover, a stick relay acting when deenergized to cause the signals for both tracks to be held at stop, pick up circuit means for said stick relay closed only providing both of said detector track sections are unoccupied, and stick circuit means for said stick relay opened when either of the track switches at the opposite end of the crossover is operated to a reverse position, whereby the contemporaneous operation of a track switch to a reverse position with the occupied condition of either detector track section causes the signals for both tracks to be held at stop until both detector track sections become unoccupied irrespective of the prior return of both track switches to their normal positions.

10. In a track circuit organization for a crossover connecting two parallel tracks with signals for governing traffic over each of the tracks, a detector track section associated with each of the track switches at the opposite ends of the crossover, a stick relay, circuit means for the signal of each track for allowing such signal to be cleared onl providing saidstick relay is energized and the detector track section of the associated track is unoccupied, a normally energized stick circuit means for said stick relay deenergized when either of the track switches at the ends of the crossover is operated to a reverse position, and pick-up circuit means for effecting the reenergization of said stick relay only providing there is no train occupying said crossover, whereby the operation of either track switch to a reverse position causes the signals for both tracks to be held at stop until said crossover is unoccupied irrespective of the return of that track switch of the crossover to its normal position.

11. In combination, two parallel railway tracks each provided with an insulated track section, a crossover having a track switch at each end for connecting said two track sections, a signal associated with each of said track sections, a track circuit for each section including the rails of that section and the rails of said crossover on the adjoining side of a common intermediate point of said crossover as well as the usual track relay and source of track circuit current, means efiective when either or both of said track switches of said crossover are operatedto reversed positions for opening both said track circuits and for holding both said signals at stop, and means initially conditioned by the operation of either or both said switches to reverse positions for requiring both said track sections to be unoccupied subsequent to the restoration of both said switches to their normal positions before either of said signals can be cleared.

ANDREW LANGDON. 

